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Model S P100D mph charging rate with the included 32 amp cable
- Thread starter audiofan
- Start date
1. No. Only the 100 kWh models had 72A chargers. The 75kWh models had 48A chargers. Now it’s all 48A.
2, Some 14-50s were on 40A circuits and some were poorly wired. 32A was safer. Canada started requiring that a few years ago.
Ulmo
Active Member
Many household wiring installations are wired poorly, so reducing the amps of the charger reduces Tesla's liability due to the lower number of fires. That's why Tesla continues to lower the speed of their chargers. The same problem happens on the grid, and I'm sure utilities hustled Tesla on this matter, especially since Tesla is a customer of and a potential supplier to utilities. (Transformers can overheat and even explode and even start fires. I'm super scared of the day someone figures out Teslas parked at home charging are what caused a forest fire that killed lots of people and ruined lots of forest and polluted a lot of air. Utilities have been playing fast and loose for a long time, and refuse to upgrade their grids to be safe, and like to blame others for their own failures (remind you of anyone?).)
Any time you are increasing speed of charging, you are increasing the energy and/or heat, and therefore, your finances required to bottle up that energy and/or heat. In the case of wiring, it means thicker wires, better wire insulation, and all that jazz (in an oversimplifying way of putting it, thicker wire doesn't let the heat bunch up in the wire and melt bad insulation and cause a short and fire -- it distributes the heat across a larger amount of metal, and the snowball effect of runaway heating doesn't happen in the wire -- I'm oversimplifying a bit; any temperature the wire gets to is OK if the wire metal and the wire insulation don't melt or conductively change shape or get hot enough to burn anything).
Basically, you would have to shell out more money to an electrician to install higher capacity wiring. If you're already doing a $ per mile calculation, then it opens up the calculations for installing a Tesla Wall Connector with associated electricians and materials. Model S/X/3 Wall Connector The older version I bought goes all the way up to 80 amps, which only the original dual-charger Model S's could handle (pre-Model X). This could trigger a house breaker box upgrade, and/or a utility connection upgrade.
It's basically a $-in speed-out equation, and you can juggle various options and match up a pair you like.
Also, you can upgrade your home, and the utility can sign off on it, and then you draw in more power than the grid actually ought to give you considering the amount of work the utility actually did. In my home, charging my Tesla Model S at only 48 amps would bring the utility volts down to 212 volts while charging compared to a high of 245 volts when not charging. I traced the problem to insufficient grid wiring on the PG&E end (charging my Tesla would cause all the homes to have a much lower voltage), all because PG&E had too many homes going to one undersized transformer with undersized wire. Higher voltage 3 phase wiring is available at the PG&E pole across the street from me, but tapping into it would require new transformer(s), and once again, more $, and since I'd be sharing with the local water district, they might even deny me (due to utility resilience questions). One way around all this would be to install a 15kW or larger solar array and charge at 60 amps during the day, or if charging at night, charge up some PowerWalls (say, a bank of 9 of them), and then dump that into the car at night using new home wiring, and avoid needing the utility at all. The cost of that would be around $200,000. I could add that to a three phase system from the pole of PG&E and get into the $400,000 territory if I wanted. Even after all that, there's no guarantee some electrician didn't drop a shard of wire in their work or a battery catch fire, and cause a huge fire, despite everything being done close to super well.
Or, I could just hire a proper install of a Tesla Wall Connector and be content with somewhere around 32 to 40 amps (which I already did two years ago).
Any time you are increasing speed of charging, you are increasing the energy and/or heat, and therefore, your finances required to bottle up that energy and/or heat. In the case of wiring, it means thicker wires, better wire insulation, and all that jazz (in an oversimplifying way of putting it, thicker wire doesn't let the heat bunch up in the wire and melt bad insulation and cause a short and fire -- it distributes the heat across a larger amount of metal, and the snowball effect of runaway heating doesn't happen in the wire -- I'm oversimplifying a bit; any temperature the wire gets to is OK if the wire metal and the wire insulation don't melt or conductively change shape or get hot enough to burn anything).
Basically, you would have to shell out more money to an electrician to install higher capacity wiring. If you're already doing a $ per mile calculation, then it opens up the calculations for installing a Tesla Wall Connector with associated electricians and materials. Model S/X/3 Wall Connector The older version I bought goes all the way up to 80 amps, which only the original dual-charger Model S's could handle (pre-Model X). This could trigger a house breaker box upgrade, and/or a utility connection upgrade.
It's basically a $-in speed-out equation, and you can juggle various options and match up a pair you like.
Also, you can upgrade your home, and the utility can sign off on it, and then you draw in more power than the grid actually ought to give you considering the amount of work the utility actually did. In my home, charging my Tesla Model S at only 48 amps would bring the utility volts down to 212 volts while charging compared to a high of 245 volts when not charging. I traced the problem to insufficient grid wiring on the PG&E end (charging my Tesla would cause all the homes to have a much lower voltage), all because PG&E had too many homes going to one undersized transformer with undersized wire. Higher voltage 3 phase wiring is available at the PG&E pole across the street from me, but tapping into it would require new transformer(s), and once again, more $, and since I'd be sharing with the local water district, they might even deny me (due to utility resilience questions). One way around all this would be to install a 15kW or larger solar array and charge at 60 amps during the day, or if charging at night, charge up some PowerWalls (say, a bank of 9 of them), and then dump that into the car at night using new home wiring, and avoid needing the utility at all. The cost of that would be around $200,000. I could add that to a three phase system from the pole of PG&E and get into the $400,000 territory if I wanted. Even after all that, there's no guarantee some electrician didn't drop a shard of wire in their work or a battery catch fire, and cause a huge fire, despite everything being done close to super well.
Or, I could just hire a proper install of a Tesla Wall Connector and be content with somewhere around 32 to 40 amps (which I already did two years ago).
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whitex
Well-Known Member
No, all new single phase markers (like US) come with 48A chargers. Until recently 100's came with 72A, and farther in the past you had a choice between 48A and 72A, and even farther back 40A and 80A.
The main reason is safety. There were a few fires. Notice that they software limited the 40A UMC in Canada to 32A long time ago. This has to do with the fact that there isn't a common NEMA 40A socket, so a number of electrical codes allow installation of a NEMA 14-50 (50A) socket on a 40A circuit and breaker. In such configuration is it only safe to draw 32A (80%) continuous loads. Since there is no way for 40A Tesla UMC to tell whether it's in a 40A or 50A circuit, Tesla started to limit them to 32A. While cost optimizing the Model 3, they realized a 32A charger would be much cheaper ($300 vs. $550) so they made it standard. Notice that they still sell the 40A version of the UMC, now called "corded", for those who use it at home on an actual 50A circuit.
No hidden strategy, though I'm sure they recommend that you use a properly installed HPWC where you charge your car daily. Even on a 50A circuit it's a more solid, dedicated charging setup.
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Ulmo
Active Member
Everything stated is exactly correct, except for the Canada stuff that I just learned about, but makes perfect sense.
A few years ago, it was still possible to get yourself into really messy situations. It was possible to pull 40 amps from much smaller circuits that obviously weren't able to handle the load. (I accidentally did this for a few seconds on a 30 amp dryer circuit at a friend's house while visiting, until I realized what I had done and immediately shut it off and freaked the heck out.) Fires could easily result, and according to that poster, have. Charging cars requires thick cables from the beginning of the circuit to the end and everything in between, every single spot, especially the hard to get to parts behind the wall you don't see, and every little tiny connection.
Just thinking about it, I'd never install any car charging circuit that wasn't 100% steel conduit beginning to end, with highly rated wire and highly rated conduit (minimum plus one or two steps), and terminating in the highest amp rated Tesla Wall Connector money could buy, and then actually charge my car at a few notches below the max installed rating, or even lower, just to reduce problems. The whole chic of installing the smallest diameter weakest conduit on the market and smallest diameter weakest wiring on the market that the spec allows is insane in my opinion. Lowest-costing this is just bad for safety. I'd rather have a 2" steel conduit end to end and put thick wire (THHN is likely fine) in there, with maybe a downsizing nipple for the Tesla Wall Connector (since I think its knockout is around 1" or something). Since installations require an off switch near the Wall Connector, I'd put a circuit breaker box next to it to do that. Depending on your installation, 1.5" steel conduit might still be a much better option than their minimum code requirements. All wiring and connectors also need to be similarly highly rated. Even with big steel pipe, under-spec'd wire or equipment or a wiring error could still cause fire.
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BigNick
Infamous Fat Sweaty Guy
So it seems like I pissed away a good chunk of change to have a 400A service upgrade and a dedicated 100A circuit (90 feet of steel-conduit 2-gauge wiring) run to my HPWC that won’t ever be used to near its maximum capacity, considering new Teslas won’t be able to use more than 48A (60A circuit required).
But at least I have peace of mind. I guess that’s worth something.
But at least I have peace of mind. I guess that’s worth something.
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@audiofan, I just rechecked my settings. I charge at 34 Amps, constant 242/3 volts. This yields 23 MPH of charge for my set up. The charger is on a 50 Amp Circuit set 40 Amps max. Since I charge over night at the reduced Kw/hr rate, I just plug in and leave to start at 11PM, I hadn't paid much attention to the mph gained. It appears at 32 amps, you are close to the right charge rate. I seldom charge during the day, so it's no issue for me. I hope one of the cables (32 or 40) will meet your needs.
whitex
Well-Known Member
Don't worry. It sounds like you don't have a Tesla on order yet (if you do, you'll get the charger available at order time, so it your ordered a 100 a month ago you're still getting 72A). If you don't know when you'll be ordering yet, by the time you buy, 72A charging may become available again, Tesla changes things often. I also wouldn't be surprised if you could still have the service center upgrade from 48 to 72A for a price (it used to cost $1,500+tax). Also, there are more EVs coming into the market, your house will be ready for any of them. So no, you didn't piss away a good chunk of change. I suspect you upgraded when building a house (why else would you spend the money before even ordering a Tesla), so it's cheaper than upgrading an existing home.
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whitex
Well-Known Member
It's rated less efficient, however in practice if you drive it like an 85D, the efficiency will be close to the 85D efficiency. I made a few trips with my wife, driving P85DL and S75D caravan style, and the two cars had almost identical Wh/mile. It could be that on the highway the rear motor sleeps most of the time anyways, and both cars have the same front motor.
whitex
Well-Known Member
While I agree with you that some home wirings are inferior and some potentially dangerous, utilities pay more attention to this stuff. While poor utilities may oversubscribe and provide poor quality with occasional brownouts, they are protected against fires and such much better than homes. If, as you stated, charging a Model S at 48A lowers the voltage from 245V to 212V for the entire neighborhood, then you have a huge problem. If there are 50 houses in the neighborhood, each turning on an extra hair blower or higher (vacuum, range, oven, ac, space heater) would cause a higher cummulative additional load than just your Model S. You should be experiencing blackouts all the time! If you don't, something doesn't add up.
Btw, by code you should be able to safely sustain 80% of your home service capacity. If you have a 100A service, 48A might put you over the 80A sustained limit.
It is a cost cutting measure for sure. But I disagree that Tesla is "cheaping out" or short changing their customers. 32amps is more than sufficient to recharge at home after a typical commute or even a long commute. While there is an element of pushing the wall connector to increase revenue per customer the reality I found is that charging rate anxiety was like range anxiety, most customers were worried at first and then realized they had enough range/charging rate.
BigNick
Infamous Fat Sweaty Guy
2014 S 85 CPO bought last November. Had the electrical work done about a month after purchasing the car. It was an upgrade to the existing electrical service at a 30-year old house. If I ever get a second Tesla, the circuit will support a 2nd WC.
whitex
Well-Known Member
Sounds like you upgraded for your current car, which still can charge up to 80A (if it has dual chargers, which I think you can still add for $2,000). You are also correct about being able to add a second HPWC onto the same circuit if you get a second Tesla - Gen2 HPWC's can load balance on the same circuit up to 4 cars. So not really a waste of money.
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